# trigonometric substitution-another problem

• Mar 23rd 2011, 08:06 AM
bcahmel
trigonometric substitution-another problem
Attachment 21233

I hope its ok I put it as an attachment- I'm really slow/bad at typing in TEX...

but basically I got stuck where I integrate 1/sec^2theta...I feel like something went wrong when I got this...
• Mar 23rd 2011, 08:15 AM
TheEmptySet
Quote:

Originally Posted by bcahmel
Attachment 21233

I hope its ok I put it as an attachment- I'm really slow/bad at typing in TEX...

but basically I got stuck where I integrate 1/sec^2theta...I feel like something went wrong when I got this...

You are fine! You just need to draw a right triangle.

Attachment 21234

http://www.mathhelpforum.com/math-he...2&d=1300896836

From the above diagram you can see that

$\displaystyle \displaystyle \sin(\theta)=\frac{x}{\sqrt{x^2+16}}$ and
$\displaystyle \displaystyle \cos(\theta)=\frac{4}{\sqrt{x^2+16}}$

Now just sub all of this in
• Mar 23rd 2011, 08:21 AM
bcahmel
thank you! :) I was convinced i had it wrong...but there are so many steps to these problems.